Cable Cross-Linked Foam Insulation Gas Retention
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Solution Overview
Problem
Existing low-voltage power cables with foamed and reticulated insulating layers have non-optimized dielectric and mechanical properties, and the manufacturing process is complex and restrictive.
Innovation Solution
A cable design featuring a foamed and cross-linked insulating layer composed of a polymeric material with a crosslinking agent that releases gas during decomposition, accompanied by an extruded impermeable layer to retain the gas, ensuring good mechanical strength and dielectric properties, with a two-layer or single-layer insulation configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a foamed and reticulated insulating layer is used in low-voltage power cables, then the cable weight is reduced and flexibility is improved, but the dielectric and mechanical properties are non-optimized
Solution Approach 1:
The patent optimizes the foaming process parameters including density variation (5-80% porosity), cell size distribution, and cross-linking degree to achieve both weight reduction and maintained mechanical strength. The controlled foaming creates a reticulated structure with specific pore characteristics that preserve dielectric properties while reducing density.
Solution Approach 2:
The insulating layer combines foamed polymer matrix with cross-linking agents and reinforcing fillers to create a composite structure. This composite approach maintains mechanical strength and dielectric breakdown voltage while achieving the desired weight reduction through the foamed structure.
2Reliability
If a complex manufacturing process with multiple steps is used to create foamed and reticulated insulating layers, then the dielectric properties can be improved, but the manufacturing complexity and time increase significantly
Solution Approach 1:
The patent combines the foaming process and cross-linking process into a single integrated manufacturing step. The cross-linking agent is incorporated into the polymer compound before extrusion, allowing simultaneous foaming and cross-linking during one heating cycle, thereby eliminating separate manufacturing steps while achieving optimized dielectric properties.
Solution Approach 2:
The cross-linking agent is pre-mixed and distributed uniformly throughout the polymer compound before extrusion. This preliminary distribution ensures homogeneous cross-linking during the foaming process, eliminating the need for subsequent treatment steps and simplifying the manufacturing process.
3Strength
If gas is released during crosslinking agent decomposition to create foam structure, then the insulating layer achieves good mechanical strength and light weight, but gas permeability becomes a critical control parameter
Solution Approach 1:
The patent utilizes controlled porous foam structure with specific porosity (5-80%) and cell size distribution to achieve the desired mechanical strength and light weight. The porous structure is optimized to maintain adequate gas barrier properties while providing the required mechanical performance for cable insulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in a cable with improved mechanical strength and dielectric properties, simplified manufacturing, and enhanced gas impermeability, specifically achieving a density variation of up to 20% and hot creep under load of less than 175% according to standard IEC 60811-507.
Implementation Method 1
a first crosslinking agent capable of releasing at least a gas during its decomposition to obtain the first layer
Implementation Method 2
an extruded layer, impermeable to said gas capable of being released during the decomposition of the first crosslinking agent
Data Source
AI summary
The present invention relates to a cable (1, 2) comprising an elongate conductive element (11, 21) encircled by at least one electrically insulating cross-linked foam first layer (12, 22) obtained from a first composition comprising a first polymer, a first cross-linking agent able to liberate at least one gas during its decomposition to obtain the first layer and optionally a nucleation agent, characterised in that it furthermore comprises an extruded layer (13, 22) that is impermeable to said gas that is liable to be given off during the decomposition of the first cross-linking agent to obtain the first layer.